I would agree that in both Akka and Erlang message passing works in an asynchronous way.
For me the difference is more that Akka has a push-style approach to message processing in the receiver (the receive message is automatically called) whereas Erlang and also e.g. the F# Mailboxprocessor use a pull-style appproach (you call receive to fetch a message). I like the latter approach better, because it allows one to start also different asynchronous operations which won't be interrupted by the reception of a new message.
That's not what I meant. Message receive in Erlang is blocking (synchronous), just like it is in Go and Quasar. Meaning, it's basically a blocking queue rather than the asynchronous/push-style/callback approach used in Akka.
For me the difference is more that Akka has a push-style approach to message processing in the receiver (the receive message is automatically called) whereas Erlang and also e.g. the F# Mailboxprocessor use a pull-style appproach (you call receive to fetch a message). I like the latter approach better, because it allows one to start also different asynchronous operations which won't be interrupted by the reception of a new message.